Causes |
1. Degenerative – old 2. Congenital (bileaflet) – young 3. Rheumatic – indigenous or third world |
Natural history |
· Progressive deterioration · Minimal increase in gradient until 50% loss of area · Each year: velocity ↑0.3m/s, AVA ↓0.1cm2 , grad ↑4-7mmHg · Death within 5 years of symptom onset |
Secondary effects |
· Diastolic dysfunction · Systolic dysfunction · Myocardial ischaemia · Pulmonary hypertension |
Associations |
· Ischaemic heart disease · Other valve disease (esp if rheumatic) · Acquired vWD · Mucosal and gastrointestinal angiodysplasias |
Significance |
· Poor correlation with severity of disease |
History |
· Angina · Syncope · Dyspnoea |
Examination |
Aortic stenosis: · Small volume, slow-rising pulse · Hyperdynamic, displaced apex beat · Harsh ESM at RUSB -> carotid, ± thrill Severe disease: · Weak pulse · Late-peaking murmur · Thrill · Soft S2 |
ECG |
· LVH (high voltage) · Strain (ST depression + T wave inversion) |
Suggestive |
· PLAx and PSAx views · Thickened · Restricted · Bileaflet · LVH · LAE |
Diagnostic |
· A5C view · Continuous wave doppler through LVOT · Peak velocity >2 |
Complications |
· Diastolic dysfunction: A4C view – abnormal E/A, ↑E/E’ · Systolic dysfx: PLAx and PSAx views – reduced motion · PHTN: A4C view – CWD at TR jet > 2.8m/s |
|
Velocity |
Mean gradient |
Valve area |
Mild |
2-3 |
5-20 |
1.5-2.5 |
Moderate |
3-4 |
20-40 |
1.0-1.5 |
Severe |
>4 |
>40 |
<1 |
Ischaemia risk |
· ↑Demand: hypertrophy + pressure work · ↓Supply: if hypotension (common in anaesthesia) |
Low cardiac output |
· Dependent on SVR for mAP |
Fixed cardiac output |
· Dependent on HR for CO |
Diastolic dysfunction |
· Dependent on preload, but also risk of pulmonary congestion · Dependent on sinus rhythm |
Pulmonary HTN |
· See other document · Maintain coronary perfusion · Minimise afterload i.e. PVR |
Goals |
· Full: euvolaemia for preload · Slow: normal HR for filling time, sinus rhythm for atrial kick · Tight: maintain SVR hence mAP hence coronary perfusion |
Access |
· Arterial line pre-induction · Large IV + pumpset · ±CVC if impaired systolic function |
Monitoring |
· Standard · 5 lead ECG · Arterial line · PPV |
Induction drugs |
· Don’t do a spinal · CSL 250mL bolus · Metaraminol infusion 10mg/h · Fentanyl 5mcg/kg · Propofol 1-2mg/kg very slowly until LOC · Rocuronium 0.6mg/kg at LOC |
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